Blank of a foldable material such as cardboard and a tray erected therefrom

ABSTRACT

A blank of foldable material such as cardboard, aluminium foil or the like, which is divided by folding lines into areas for erecting a tray with a bottom, two opposite side walls with end flaps and two opposite end walls with folded down edge flaps which are adapted to lie over the folded in end flaps for the purpose of locking these. The folding line between the bottom and each of the end walls extends along an arc so that when folding up the end wall this wall and the folded down edge flap will be kept in a bent position, which locks the folded down edge flap.

United States Patent 1191 Persson BLANK OF A FOLDABLE MATERIAL SUCH AS CARDBOARD AND A TRAY ERECTED THEREFROM [75] Inventor: Karl Rune Persson, Halmstad,

Sweden [73] Assignee: Sprinter Pack AB, l-lalmstad,

Sweden [22] Filed: Sept. 5, 1973 [21] Appl. No.: 394,443

[30] Foreign Application Priority Data Sept. 13, 1972 Sweden 11806/72 [52] US. Cl. 229/31 R; 229/41 B [51] Int. Cl. B65D 5/36 [58] Field of Search 229/30, 31 R, 31 FS, 41 B [56] References Cited UNITED STATES PATENTS 3,008,626 11/1961 Lawrence 229/31 FS Dec. 23, 1975 3,767,108 10/1973 Arneson 229/31 F5 FOREIGN PATENTS OR APPLICATIONS 860,744 1/1941 France 229/34 R Primary ExaminerLeonard D. Christian Attorney, Agent, or FirmOstrolenk, Faber, Gerb & Soffen [57] ABSTRACT A blank of foldable material such as cardboard, aluminium foil or the like, which is divided by folding lines into areas for erecting a tray with a bottom, two opposite side walls with end flaps and two opposite end walls with folded down edge flaps which are adapted to lie over the folded in end flaps for the purpose of locking these. The folding line between the bottom and each of the end walls extends along an arc so that when folding up the end wall this wall and the folded down edge flap will be kept in a bent position, which locks the folded down edge flap.

7 Claims, 9 Drawing Figures US. Patent Dec. 23, 1975 Sheet1of2 3,927,823

FIG.1

US. Patent Dec. 23, 1975 Sheet20f2 3,927,823

BLANK OF A FOLDABLE MATERIAL SUCH AS CARDBOARD AND A TRAY ERECTED THEREFROM The present invention relates to a blank of a foldable material such as cardboard, which is divided by means of folding lines into areas for raising a tray with a bottom, two opposite side walls with end flaps and two opposite end walls with edge flaps folded down and overlapping the end flaps folded in for locking these.

Hitherto the end flaps and edge flaps have normally been locked by the action of an additional agent such as an adhesive or by arranging slots in the end walls.

The object of the invention is to provide a blank which can be erected to a tray with the end flaps and edge flaps locked without the assistance of an adhesive or other additional means and without the need to arrange slots in any of the tray sections.

This is achieved according to the invention by means of a blank which is characterized according to the invention by the fact that the folding line between the bottom and each of the end walls extends along an are so that when folding the adjacent end wall, this wall and the associated edge flap folded down will be held in a bent position, thus locking the folded edge flap and hence the end flaps. The invention is therefore based essentially on the fact that folding down the edge flap against a plane end wall by folding along an essentially straight folding line will not effect a locking action as long as the end wall and the edge flap are plane, whilst bending of the end wall and the edge flap when the edge flap is folded down will prevent the edge flap from dropping out away from the end wall.

The blank may be provided with known surface coats to resist liquid, the coat consisting of heat sealable plastic, which may also be of a known type, to withstand temperatures of over 200C, as is the case when the tray is to be used, for example, for ready cooked food or other food intended for heating, such as baking powder mixtures which after adding liquid can be heated and baked into cakes or bread. The tray according to the invention may also be used to advantage for ice-cream and other deep-frozen foods. It is also possible to use the materials according to the invention, which include cardboard, thin aluminium foil or similar materials, for domestic purposes where one can very easily erect the tray oneself and store food in the tray so that the tray can be placed directly into the oven for heating. After use the tray can be thrown away, thereby avoiding washing up conventional heating vessels.

An important advantage of the tray according to the invention, particularly with regard to deep-frozen foods, and the use of the tray as a baking mould, is that it can easily be opened by simply folding up the edge flaps and then folding out the end walls and side walls of the tray to release the deep-frozen goods such as ice-cream or the prepared pastry.

Some suitable embodiments of the blank and tray according to the invention are shown as examples in the accompanying drawings.

FIG. 1 shows an embodiment of the blank for the formation of a tray with tight corners, FIGS. 2, 3 and 4 show in perspective various stages of the tray during erection thereof, FIG. 5 shows one end of the erected tray seen from the inside, FIG. 6 is a perspective view of the erected tray, FIG. 7 shows an end section of another embodiment of the blank according to the invention with freely projecting end flaps, FIG. 8 shows one end of a tray erected from the blank in FIG. 7 with the end flaps on the outside of the tray, the edge flaps being folded down towards these end flaps, whilst FIG. 9 shows one end of a tray erected from the blank in FIG. 7 with the end flaps on the inside of the tray and the edge flap folded down over these end flaps.

The blank in FIG. 1 and the corresponding tray in FIGS. 2 to 6 consist of a bottom 10, two side walls 12, 14 and two end walls l6, 18. The side walls are extended with end flaps 20, which in the example shown consist of corner sections between the ends of the end walls and the side walls and can be folded along edge folding lines 22, 24 and diagonal folding lines 26 in a manner known per se.

At their upper edges the end walls are extended by edge flaps 28 which can be folded along straight, or essentially straight, transverse folding lines 30. The end wall 16 can be folded relative to the bottom 10 by folding along an arc-shaped folding line 32. The side walls have edge flanges 34 which are extended by locking flaps 35.

When the end wall 16 is folded up, it will be forced into an are shaped position, as shown in FIGS. 2 and 3, due to the fact that folding line 32 has an arcuate shape. In this position the end flaps 20 are folded in towards the outside of end wall 16 and then the edge flap 28 is folded down over the end flaps as shown in FIG. 4.

After folding down the edge flap 28 end wall 16 and the folded down edge flap 28 will be kept in the are shaped position as shown in FIGS. 5 and 6. In practice folding line 30 between edge flap 28 and end wall 16 will not normally bend out as much as folding line 32 between end wall 16 and bottom 10, but by providing bottom folding line 32 with a sufficient arc shape, sufficient bending of the edge flap folding line 30 in the erected tray is also obtained so that the edge flap can be locked in its folded down position.

The tray shown in FIG. 6 has liquid tight corners. It can easily be opened by folding up the edge flaps. If the blank has a heat sealable coat, an extra locking action can easily be obtained by heat sealing, but this should not be necessary in most cases.

FIG. 7 shows a blank corresponding to the blank in FIG. 1 with the difference that end flaps 36, which can be folded along a folding line 38, are freely projecting from the ends of the side walls, and that the side walls have no edge flaps. When erecting this blank, end flaps 36 can alternatively be placed on the outside of the end wall as shown in FIG. 8 which gives the tray a smooth inside, or end flaps 36 can be placed on the inside of the end wall as shown in FIG. 9, which gives the tray a smooth outside. In the first case edge flap 28 is folded down towards the outside of the end wall, and in the second case it is folded down towards the inside of the end wall. In both cases locking of edge flap 28 is obtained in its folded down position due to the arc-shaped bottom fold 32.

In the examples shown, bottom folding line 32 on the blank in FIGS. 1 and 7 is provided to form an are which is curved towards folding line 30 between edge flap 28 and end wall 16 so that the exterior surface of each end wall I6, 18 has a convex contour, but it is also possible to curve bottom folding line 32 in the opposite direction so that the exterior surface of each end wall 16, I8 has a concave contour and still obtain the locking action according to the invention.

I A furtherimportant advantage of the blank according to the invention is that it can have a relatively small material thickness with minimal rigidity. This does not prevent the locking action according to the invention from. being obtained for the formation of a tray with satisfactory locking action at the corners for a large number of applications.

In the examples shown, the tray walls form an essentially right angle with the bottom, but they may also incline outwards to enable the trays to be stacked on top of each other.

What is claimed is:

. l. A blank of foldable material for forming a folding tray comprising:

a bottom; opposite sidewalls articulated along a fold line at one side thereof to said bottom; an edge flange articulated along a fold line to another side of each sidewall and adapted to be folded to lie against an exterior surface of the associated sidewall; opposite endwalls articulated at one end thereof to said bottom along an arcuate-shaped folding line; an edge flap articulated to another end of each endwall along a substantially straight folding line; locking means extended from and articulated along a fold line at opposite ends of each sidewall; each sidewall and each endwall being adapted to be erected in a common direction relative to the bottom for assembly of the tray; each edge flap being folded over to lie against an adjacent endwall, each locking means being folded to lie between an adjacent endwall and the associated folded-over edge flap, whereby the curved shape of the erected edge flaps and endwalls retain the enclosed locking means therebetween to maintain the respective endwalls and sidewalls in the erected condition.

2. A blank for forming a folded tray as set forth in claim 1, wherein each arcuate-shaped folding line causes each endwall to assume a concave contour along its'exterior surface when erected.

3. A blank for forming a folded tray as set forth in claim 1,- wherein each arcuate-shaped folding line causes each endwall to assume a convex contour along its exterior surface when erected.

4. A blank for forming a folding tray as set forth in claim 1, wherein said locking means comprises locking flaps extended from and articulated along a fold line at opposite ends of each sidewall edge flange and adapted to be folded to lie between each endwall and the associated folded-over edge flap to lock the sidewalls when the folding tray is in the assembled condition.

5. A blank for forming a folding tray as set forth in claim 4, wherein said locking means further comprises articulated corner gusset means for integrally and foldably connecting each sidewall to each endwall at the corners therebetween, said corner gusset means being adapted to lie flush against an associated endwall and beneath an associated edge flap when the folding tray is in the erected condition.

6. A blank for forming a folding tray as set forth in claim 1, wherein said locking means comprises end flaps extended from and articulated along a fold line at opposite ends of each sidewall and spaced from said endwalls; said end flaps adapted to be folded to lie between each endwall and the associated folded-over edge flap to lock the sidewalls in the assembled condition.

7. A folding tray formed from a blank of foldable material comprising: a bottom; opposite sidewalls articulated along a folding line at one side thereof to said bottom; an edge flange articulated along a folding line to another side of each sidewall; locking flaps extending from and articulated to opposite ends of each edge flange along a fold line; opposite endwalls articulated at one end thereof to said bottom along an arcuateshaped folding line; and edge flap articulated to another end of each endwall along a substantially straight folding line; said edge flanges being adapted to be folded over to lie against an exterior surface of the associated sidewall with said locking flaps being adapted to be folded in towards one surface of the adjacent endwall, each edge flap being folded over to assume a curved shape and to lie against the associated endwall with the adjacent locking flaps being positioned therebetween, whereby the respective curved edge flaps and locking portions lock the respective endwalls and sidewalls in an assembled condition. 

1. A blank of foldable material for forming a folding tray comprising: a bottom; opposite sidewalls articulated along a fold line at one side thereof to said bottom; an edge flange articulated along a fold line to another side of each sidewall and adapted to be folded to lie against an exterior surface of the associated sidewall; opposite endwalls articulated at one end thereof to said bottom along an arcuate-shaped folding line; an edge flap articulated to another end of each endwall along a substantially straight folding line; locking means extended from and articulated along a fold line at opposite ends of each sidewall; each sidewall and each endwall being adapted to be erected in a common direction relative to the bottom for assembly of the tray; each edge flap being folded over to lie against an adjacent endwall, each locking means being folded to lie between an adjacent endwall and the associated folded-over edge flap, whereby the curved shape of the erected edge flaps and endwalls retain the enclosed locking means therebetween to maintain the respective endwalls and sidewalls in the erected condition.
 2. A blank for forming a folded tray as set forth in claim 1, wherein each arcuate-shaped folding line causes each endwall to assume a concave contour along its exterior surface when erected.
 3. A blank for forming a folded tray as set forth in claim 1, wherein each arcuate-shaped folding line causes each endwall to assume a convex contour along its exterior surface when erected.
 4. A blank for forming a folding tray as set forth in claim 1, wherein said locking means comprises locking flaps extended from and articulated along a fold line at opposite ends of each sidewall edge flange and adapted to be folded to lie between each endwall and the associated folded-over edge flap to lock the sidewalls when the folding tray is in the assembled condition.
 5. A blank for forming a folding tray as set forth in claim 4, wherein said locking means further comprises articulated corner gusset means for integrally and foldably connecting each sidewall to each endwall at the corners therebetween, said corner gusset means being adapted to lie flush against an associated endwall and beneath an associated edge flap when the folding tray is in the erected condition.
 6. A blank for forming a folding tray as set forth in claim 1, wherein said locking means comprises end flaps extended from and articulated along a fold line at opposite ends of each sidewall and spaced from said endwalls; said end flaps adapted to be folded to lie between each endwall and the associated folded-over edge flap to lock the sidewalls in the assembled condition.
 7. A folding tray formed from a blank of foldable material comprising: a bottom; opposite sidewalls articulated along a folding line at one side thereof to said bottom; an edge flange articulated along a folding line to another side of each sidewall; locking flaps extending from and articulated to opposite ends of each edge flange along a fold line; opposite endwalls articulated at one end thereof to said bottom along an arcuate-shaped folding line; and edge flap articulated to another end of each endwall along a substantially straight folding line; said edge flanges being adapted to be folded over to lie against an exterior surface of the associated sidewall with said locking flaps being adapted to be folded in towards one surface of the adjacent endwall, each edge flap being folded over to Assume a curved shape and to lie against the associated endwall with the adjacent locking flaps being positioned therebetween, whereby the respective curved edge flaps and locking portions lock the respective endwalls and sidewalls in an assembled condition. 